J.C. Bradbury links to a paper showing biological evidence that teams should go to a three-man rotation in the playoffs:
The authors look at a sample of pitchers and how they recover after pitching different lengths of time. The results show a few things. First, the pattern of recovery indicates most healing occurs soon after pitching, and that further recovery occurs at a diminishing rate. After three days of rest, the measures of skeletal muscle damage were back to baseline values. Second, performance on two days of rest is only slightly worse than, and not statistically distinguishable from, performance on four days of rest. This is good news for the Phillies and Roy Oswalt. The results are also consistent with my analysis (with Sean Forman) of major-league pitchers.
I hope more studies like this convince teams to return to four-man rotations during the regular season.
The issue with a four-man rotation vs. a five man rotation isn’t a concern with muscles as much as it is a concern with the number of pitches you’re putting on ligaments, tendons, and cartilage. The shoulders and elbows can only take so many pitches before they start breaking down. If you go to a four-man rotation, you’re obviously going to throw more innings and more pitches.
Four man rotations with a quicker hook for the starting pitcher. The fifth starter becomes the extra long reliever you would need if you followed that strategy.
3 days of rest seems to make a lot more sense. You have your start, take a day off, workout (or your throw day), another day off, and then your start.
When’s the last season that a team started the year with a four man rotation?
@Dave: The 1990 Oakland A’s sort of used a four-man rotation. They skipped the fifth starter when they could, one reason that Bob Welch was able to win 27 games.